Method for realizing carbon sequestration by using alkalinity source

Abstract

The invention provides a method for realizing carbon sequestration by using an alkalinity source, which comprises the following steps: (1) grinding, crushing and screening the alkalinity source to obtain alkalinity source powder; wherein the alkalinity source is prepared from peridotite, basalt, wollastonite and anorthite; (2) carrying out acid leaching on the alkalinity source powder to obtain an ore leaching suspension; reacting the mineral leaching suspension liquid with a pretreatment agent under the conditions that the temperature is 150 DEG C, the pressure is 5MPa and the liquid-solid ratio is 20: 1 to obtain a pretreated alkalinity source; (3) mixing the pretreated alkalinity source with water, and then introducing carbon dioxide gas to carry out carbonation reaction; after the reaction is finished, a gas channel is closed, and carbonate rock minerals are obtained after cooling and solid-liquid separation, so that carbon sequestration is realized, and permanent, stable and large-scale sequestration of carbon dioxide can be realized.

Description

Technical Field

[0001] The present invention relates to the technical field of carbon dioxide sequestration, and in particular, to a method for realizing carbon sequestration by using an alkalinity source. Background Art

[0002] As the content of greenhouse gases in the atmosphere gradually increases, the global climate has changed significantly, and the atmospheric concentration of carbon dioxide has increased significantly.

[0003] Currently, there are mainly three commonly used carbon dioxide control technologies in the world: (1) reducing the use of non-renewable energy sources such as fossil fuels (coal, oil, natural gas), and developing and utilizing renewable energy sources such as geothermal energy, wind energy, and biomass energy, and by changing the energy structure, reducing the proportion of primary energy consumption; (2) improving the energy conversion efficiency and advocating a green and energy-saving lifestyle; (3) carbon dioxide capture and sequestration technology (CCS). Among them, CCS technology is regarded as one of the most promising technologies to solve the greenhouse effect, and it has a certain feasibility in the treatment process of large-scale carbon dioxide sources.

[0004] The main carbon dioxide sequestration methods are geological sequestration, mineral sequestration, and ocean sequestration; among them, geological sequestration is to pressurize and inject carbon dioxide into a suitable formation, and use the pore space of the formation to store carbon dioxide; mineral sequestration is to make carbon dioxide react chemically with metal oxides to form solid carbonates and other by-products; ocean sequestration is to inject liquid carbon dioxide into deep sea waters to form a stable lake-like structure under high pressure conditions.

[0005] Mineral sequestration is to use the chemical reaction of carbon dioxide with certain minerals (such as olivine) to generate stable carbonate minerals. This method of sequestration is stable and has no leakage risk. Moreover, most of the carbon on the earth exists in the form of carbonate minerals. Sequestering carbon in the crystal structure of minerals is a long-term and reliable method. Therefore, carbon dioxide mineral sequestration is recognized as the safest and most reliable sequestration method.

[0006] Based on this, when sequestering carbon dioxide, if dry carbonation is used, that is, directly obtaining carbonates by means of a one-step gas-solid reaction. However, this method needs to be carried out under high temperature and high pressure to isolate carbon dioxide from the atmosphere. However, one of the major drawbacks of this method is that the reaction kinetics of calcium and magnesium silicates are often too slow, and accelerating the reaction kinetics by increasing the temperature is often limited by thermodynamics. Therefore, it is particularly important to seek a suitable and stable wet carbonation for carbon dioxide sequestration. Summary of the Invention

[0007] Based on the above problems, the purpose of the present invention is to provide a method for realizing carbon sequestration by using an alkalinity source, which can achieve permanent, stable and large-scale sequestration of carbon dioxide.

[0008] Therefore, the inventors sought to sequester carbon dioxide by wet carbonation. However, in the research and practice, the inventors found that during the reaction process, when calcium and magnesium ions migrate to the mineral surface, carbonate minerals will be formed, and this part of the carbonate minerals will wrap the minerals, hindering the progress of the carbonation reaction and thus affecting the sequestration effect. Therefore, in the present invention, the alkalinity source is first subjected to acid leaching pretreatment before the reaction to preferentially dissolve out some calcium and magnesium ions, and then the pretreated alkalinity source is carbonated with carbon dioxide. Carbon dioxide dissolves in the liquid phase to form carbonic acid, and carbonic acid decomposes into carbonate or bicarbonate ions; the alkalinity source dissolves out metal ions under the action of proton exchange and chemically precipitates with the carbonate or bicarbonate ions decomposed from carbonic acid to form stable carbonate rock minerals, thereby achieving carbon sequestration.

[0009] The implementation mode of the present invention is achieved through the following technical solutions:

[0010] A method for realizing carbon sequestration by using an alkalinity source, comprising the following steps:

[0011] (1) Grinding and crushing the alkalinity source and screening it to a particle size of 30 - 50 μm to obtain the alkalinity source powder; wherein, the alkalinity source includes: peridotite, basalt, wollastonite, anorthite, etc.;

[0012] (2) Subjecting the alkalinity source powder to acid leaching, with a liquid-solid ratio of 10 - 20:1 mL / g during acid leaching, to obtain a leached ore suspension; then mixing the leached ore suspension with a pretreatment agent in a mass ratio of 10 - 20:1 for reaction to obtain a pretreated alkalinity source;

[0013] (3) Mixing the pretreated alkalinity source and water in a mass ratio of 1:10 - 20 and adding them to a reaction kettle, stirring at a stirring speed of 200 - 300 r / min for 5 - 20 min, and then introducing carbon dioxide gas. Specifically, the carbon dioxide gas here can be sourced from the carbon dioxide emission tower of a thermal power plant or other carbon dioxide emission towers; and under a stirring speed of 200 - 300 r / min, at 100 - 200 °C and 5 - 10 MPa conditions, a carbonation reaction is carried out for 0.5 - 1.5 h; after the reaction is completed, the gas passage is closed, and after cooling and solid-liquid separation, carbonate rock minerals are obtained, achieving carbon sequestration.

[0014] The increase in temperature within a certain range can improve the dissolution reaction activity of the alkalinity source in the leaching suspension, accelerate the dissolution of calcium and magnesium ions, increase the concentration of calcium and magnesium ions in the solution, thereby facilitating the precipitation of calcium carbonate and magnesium carbonate and improving the carbonation conversion rate. However, excessive temperature increase will also lead to a decrease in the solubility of carbon dioxide, reducing the carbonate or bicarbonate ions in the solution and being unfavorable for the forward precipitation reaction. Therefore, the inventor controls the reaction temperature within 100 - 200 °C, enabling the maximum carbonation conversion rate of the carbonation reaction and having a good carbon sequestration effect. Preferably, the temperature is controlled at 15 - 180 °C for the best result. The same applies to pressure. By controlling within the carbonation conversion rate range, it accelerates the dissolution of calcium and magnesium ions and also generates more carbonate or bicarbonate ions, making the carbonation reaction more efficient.

[0015] Among them, during the acid leaching pretreatment, depending on the different alkalinity sources, different acid solutions are used, specifically as follows: sulfuric acid is used for the pretreatment of olivine, hydrochloric acid for the pretreatment of basalt, hydrochloric acid for the pretreatment of wollastonite, and acetic acid for the pretreatment of anorthite.

[0016] Among them, depending on the different alkalinity sources, different pretreatment agents are used, specifically as follows:

[0017] Under the condition of pH being 10 - 11, the pretreatment agents added to the leaching suspensions of olivine and anorthite are: 0.50 mol / L NaHCO3 and 1.00 mol / L NaCl;

[0018] Under the condition of pH being 10, the pretreatment agent added to the basalt leaching suspension is: 0.50 mol / L NaHCO3;

[0019] Under the condition of pH being 10, the pretreatment agents added to the wollastonite leaching suspension are: 0.50 mol / L NaHCO3 and 0.25 mol / L NaCl.

[0020] By using NaHCO3, the bicarbonate ions in the solution are maintained at a relatively high concentration, which can not only promote the reaction but also well regulate the pH change caused by the dissolution of carbon dioxide, reducing the resistance during the formation of calcium carbonate and magnesium carbonate. The addition of NaCl can increase the solubility of silicate minerals, thereby promoting the leaching of calcium and magnesium ions and facilitating the occurrence of the reaction. When NaHCO3 and NaCl are used in combination, their synergistic effect further improves the carbonation conversion rate, mainly because NaCl is completely ionized in the suspension, fully exerting the role of salt ions, and while promoting the dissolution of wollastonite, it also increases the solubility of calcium carbonate.

[0021] In addition, the mass ratio of the leaching suspension to the pretreatment agent is controlled to be 10-20:1. The increase in the liquid-solid ratio not only facilitates the dispersion of the alkalinity source but also reduces the encapsulation of the generated carbonate minerals on the mineral surface, thereby improving the carbonation reaction efficiency and generating more carbonate minerals within a certain period of time.

[0022] Finally, it should be noted that the carbon dioxide gas of the present invention can be sourced from the carbon dioxide emission tower of a thermal power plant or other carbon dioxide emission points, such as power plants, metallurgical plants, refineries, etc. Preferably, the carbon emission point itself can generate an alkalinity source. Especially in mines, the surrounding rocks in many mining areas are rocks such as peridotite and basalt, and there is a large amount of carbon emissions in the downstream ore dressing and metallurgical processes. The two factory areas are generally very close, which can reduce carbon emissions in each process; the same is true for coal mines. While carrying out carbon emission mining, the permanent sequestration of carbon dioxide is achieved, and thus the development goal of "green and low-carbon" is realized.

[0023] The technical solutions of the embodiments of the present invention have at least the following advantages and beneficial effects:

[0024] 1. The present invention sequesters carbon dioxide in the form of wet carbonation, and pre-treats the alkalinity source by acid leaching before the reaction, preferentially dissolving some calcium and magnesium ions first to avoid the migration of calcium and magnesium ions to the surface of the alkalinity source minerals to form carbonate minerals during the reaction, which would hinder the subsequent carbonation reaction and affect the sequestration effect; then, the pre-treated alkalinity source is subjected to a carbonation reaction with carbon dioxide to form stable carbonate rock minerals, thereby achieving carbon sequestration.

[0025] 2. When the present invention performs acid leaching, different acids are used to treat different alkalinity sources first, and then mixed with different pretreatment agents to obtain a pre-treated alkalinity source, so that during the carbonation reaction process, while improving the carbonation conversion rate, the carbon sequestration amount can also be increased, thereby achieving the permanent, stable and large-scale sequestration of carbon dioxide. Specific Embodiments

[0026] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below. Those not specified in the embodiments are carried out according to conventional conditions or conditions recommended by the manufacturer. The reagents or instruments not specified by the manufacturer are all conventional products that can be obtained through commercial purchase.

[0027] Example 1

[0028] A method for realizing carbon sequestration using an alkalinity source, comprising the following steps:

[0029] (1) Grind and crush the alkalinity source and screen it to a particle size of 38 μm to obtain the alkalinity source powder; wherein, the alkalinity source includes: peridotite, basalt, wollastonite, anorthite;

[0030] (2) Acid-leach the alkalinity source powder. The liquid-solid ratio during acid leaching is 10:1 mL / g to obtain the ore-leaching suspension; then mix the ore-leaching suspension with the pretreatment agent in a mass ratio of 20:1 for reaction to obtain the pretreated alkalinity source;

[0031] Among them, during acid leaching: use sulfuric acid to pretreat olivine, hydrochloric acid to pretreat basalt, hydrochloric acid to pretreat wollastonite, and acetic acid to pretreat anorthite;

[0032] The pretreatment agent varies according to the different alkalinity sources, and the specific details are as follows:

[0033] Under the condition of pH = 11, the pretreatment agent added to the ore-leaching suspensions of olivine and anorthite is: 0.50 mol / L NaHCO3 and 1.00 mol / L NaCl;

[0034] Under the condition of pH = 10, the pretreatment agent added to the ore-leaching suspension of basalt is: 0.50 mol / L NaHCO3;

[0035] Under the condition of pH = 10, the pretreatment agent added to the ore-leaching suspension of wollastonite is: 0.50 mol / L NaHCO3 and 0.25 mol / L NaCl;

[0036] (3) Mix the pretreated alkalinity source and water in a mass ratio of 1:20 and add them to a reaction kettle. Stir at a stirring speed of 260 r / min for 10 min, then introduce the carbon dioxide gas from the carbon dioxide emission tower of the thermal power plant, and under a stirring speed of 240 r / min, carry out a carbonation reaction at 180 °C and 8 MPa for 1 h; after the reaction is completed, close the gas channel, and after cooling and solid-liquid separation, carbonate rock minerals are obtained, realizing carbon sequestration.

[0037] Example 2

[0038] A method for realizing carbon sequestration using an alkalinity source, comprising the following steps:

[0039] (1) Grind and crush the alkalinity source and screen it to a particle size of 33 μm to obtain the alkalinity source powder; wherein, the alkalinity source includes: peridotite, basalt, wollastonite, anorthite;

[0040] (2) Acid-leach the alkalinity source powder. The liquid-solid ratio during acid leaching is 15:1 mL / g to obtain the ore-leaching suspension; then mix the ore-leaching suspension with the pretreatment agent in a mass ratio of 20:1 for reaction to obtain the pretreated alkalinity source;

[0041] Among them, during acid leaching pretreatment: olivine is pretreated with sulfuric acid, basalt is pretreated with hydrochloric acid, wollastonite is pretreated with hydrochloric acid, and anorthite is pretreated with acetic acid;

[0042] The pretreatment agent varies according to the alkalinity source, and the specific details are as follows:

[0043] Under the condition of pH = 10, the pretreatment agents added to the ore-leaching suspensions of olivine and anorthite are: 0.50 mol / L of NaHCO3 and 1.00 mol / L of NaCl;

[0044] Under the condition of pH = 10, the pretreatment agent added to the ore-leaching suspension of basalt is: 0.50 mol / L of NaHCO3;

[0045] Under the condition of pH = 10, the pretreatment agents added to the ore-leaching suspension of wollastonite are: 0.50 mol / L of NaHCO3 and 0.25 mol / L of NaCl;

[0046] (3) Mix the pretreatment alkalinity source and water in a mass ratio of 1:20 and add them to a reaction kettle. Stir at a stirring speed of 200 r / min for 20 min, then introduce the carbon dioxide gas from the carbon dioxide emission tower of a thermal power plant, and carry out a carbonation reaction at 120 °C and 6 MPa under a stirring speed of 280 r / min for 1 h; after the reaction is completed, close the gas passage, and after cooling and solid-liquid separation, carbonate rock minerals are obtained, realizing carbon sequestration.

[0047] Example 3

[0048] A method for realizing carbon sequestration using an alkalinity source, comprising the following steps:

[0049] (1) Grind and crush the alkalinity source and screen it to a particle size of 42 μm to obtain the alkalinity source powder; among them, the alkalinity source includes: olivine, basalt, wollastonite, anorthite;

[0050] (2) Acid-leach the alkalinity source powder with a liquid-solid ratio of 10:1 mL / g during acid leaching to obtain an ore-leaching suspension; then mix the ore-leaching suspension and the pretreatment agent in a mass ratio of 20:1 for reaction to obtain a pretreated alkalinity source;

[0051] Among them, during acid leaching pretreatment: olivine is pretreated with sulfuric acid, basalt is pretreated with hydrochloric acid, wollastonite is pretreated with hydrochloric acid, and anorthite is pretreated with acetic acid;

[0052] The pretreatment agent varies according to the alkalinity source, and the specific details are as follows:

[0053] Under the condition of pH = 10.5, the pretreatment agents added to the olivine and anorthite leaching suspensions are: 0.50 mol / L NaHCO3 and 1.00 mol / L NaCl;

[0054] Under the condition of pH = 10, the pretreatment agent added to the basalt leaching suspension is: 0.50 mol / L NaHCO3;

[0055] Under the condition of pH = 10, the pretreatment agents added to the wollastonite leaching suspension are: 0.50 mol / L NaHCO3 and 0.25 mol / L NaCl;

[0056] (3) Mix the pretreatment alkalinity source and water in a mass ratio of 1:20 and add them to the reaction kettle. Stir at a stirring speed of 300 r / min for 5 min, then introduce the carbon dioxide gas from the carbon dioxide emission tower of the thermal power plant, and under the stirring speed of 200 r / min, carry out a carbonation reaction at 160 °C and 7 MPa for 1 h; after the reaction is completed, close the gas passage, and after cooling and solid-liquid separation, carbonate rock minerals are obtained, realizing carbon sequestration.

[0057] Comparative Example 1

[0058] The difference between this comparative example and Example 1 is that: step (2) is not included.

[0059] Comparative Example 2

[0060] The difference between this comparative example and Example 1 is that: in step (2), the alkalinity source powder is not acid-leached.

[0061] Comparative Example 3

[0062] The difference between this comparative example and Example 1 is that: in step (2), the leaching suspension does not react with the pretreatment agent.

[0063] Experimental Example

[0064] 1. Test the carbonation conversion rate and carbon sequestration amount in each example and comparative example respectively, and the test results are shown in Table 1; among them, the test method for the carbonation conversion rate is as follows: measure the initial CO2 amount before the reaction (gas chromatography method); after the reaction, filter the solid product, and measure the released CO2 amount after acidolysis (hydrochloric acid titration method); conversion rate = (amount of CO2 consumed in the reaction / initial CO2 amount) × 100%; the test method for the carbon sequestration amount is as follows: determine the total amount of carbonates in the product by chemical analysis, and convert it to the CO2 sequestration amount in combination with the molar mass, specifically as follows: extract and purify the carbonate product; calculate the corresponding CO2 amount through stoichiometric relations.

[0065] Table 1 - Test Results of Each Example and Comparative Example

[0066] Carbonation conversion rate (%) Carbon sequestration amount (mol / kg) Example 1 91.5 9.23 Example 2 90.8 9.20 Example 3 91.2 9.21 Comparative Example 1 58.6 5.2 Comparative Example 2 36.2 3.1 Comparative Example 3 25.7 2.4

[0067] As can be seen from the results in Table 1: Before the reaction, the alkalinity source of the present invention is first subjected to acid leaching pretreatment to preferentially dissolve some calcium and magnesium ions, and then the pretreated alkalinity source is carbonated with carbon dioxide, thereby realizing carbon sequestration. More importantly, the carbonation conversion rate and carbon sequestration amount are improved; it is avoided that during the direct carbonation reaction of the alkalinity source with carbon dioxide, calcium and magnesium ions migrate to the mineral surface and carbonate minerals will be formed. This part of the carbonate minerals will wrap the minerals and hinder the progress of the carbonation reaction, thereby affecting the sequestration effect.

[0068] The above are only the preferred embodiments of the present invention and are not intended to limit the present invention. For those skilled in the art, the present invention can have various changes and modifications. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principle of the present invention shall be included within the protection scope of the present invention.

Claims

1. A method for carbon sequestration using an alkalinity source, characterized in that, It includes the following steps: (1) Grind and crush the alkalinity source and screen it to a particle size of 30 - 50 μm to obtain the alkalinity source powder; (2) Acid-leach the alkalinity source powder to obtain a leaching ore suspension; Then react the leaching ore suspension with a pretreatment agent at 150 °C, 5 MPa, and a liquid-solid ratio of 20:1 to obtain a pretreated alkalinity source; (3) Mix the pretreated alkalinity source and water, and then introduce carbon dioxide gas for carbonation reaction; after the reaction ends, close the gas passage, and after cooling and solid-liquid separation, carbonate rock minerals are obtained to achieve carbon sequestration.

2. The method for carbon sequestration using an alkalinity source according to claim 1, characterized in that, In step (1), the alkalinity source is ground and crushed and screened to a particle size of 30 - 50 μm.

3. The method for carbon sequestration using an alkalinity source according to claim 1, wherein In step (1), the alkalinity source includes: peridotite, basalt, wollastonite, anorthite.

4. The method for realizing carbon sequestration by using an alkalinity source according to claim 1, characterized in that, In step (2), when acid-leaching the alkalinity source powder, different acid solutions are used according to the different alkalinity sources, specifically as follows: use sulfuric acid to pretreat olivine, hydrochloric acid to pretreat basalt, hydrochloric acid to pretreat wollastonite, and acetic acid to pretreat anorthite.

5. The method for carbon sequestration using an alkalinity source according to claim 4, wherein In step (2), when the leaching ore suspension reacts with the pretreatment agent, different pretreatment agents are used according to the different alkalinity sources, specifically as follows: the pretreatment agents added to the leaching ore suspensions of olivine and anorthite are: 0.50 mol / L NaHCO3 and 1.00 mol / L NaCl; the pretreatment agent added to the leaching ore suspension of basalt is: 0.50 mol / L NaHCO3; the pretreatment agents added to the leaching ore suspension of wollastonite are: 0.50 mol / L NaHCO3 and 0.25 mol / L NaCl.

6. The method for carbon sequestration using an alkalinity source according to claim 1, wherein In step (2), the liquid-solid ratio during acid-leaching is 10 - 20:1 mL / g.

7. The method for carbon sequestration using an alkalinity source according to claim 1, wherein In step (2), the mass ratio of the leaching ore suspension to the pretreatment agent is 10 - 20:

1.

8. The method for carbon sequestration using an alkalinity source according to claim 1, characterized in that, In step (3), the reaction conditions for the carbonation reaction are: 100 - 200 °C, 5 - 10 MPa.

9. The method for carbon sequestration using an alkalinity source according to claim 1, wherein In step (3), during the carbonation reaction, the reaction is carried out at a stirring speed of 200 - 300 r / min for 0.5 - 1.5 h.

10. The method for carbon sequestration using an alkalinity source according to claim 1, wherein, In step (3), the carbon dioxide gas is sourced from a carbon dioxide emission tower.